/*
 * @lc app=leetcode.cn id=17 lang=typescript
 *
 * [17] 电话号码的字母组合
 *
 * https://leetcode.cn/problems/letter-combinations-of-a-phone-number/description/
 *
 * algorithms
 * Medium (59.84%)
 * Likes:    2840
 * Dislikes: 0
 * Total Accepted:    894.2K
 * Total Submissions: 1.5M
 * Testcase Example:  '"23"'
 *
 * 给定一个仅包含数字 2-9 的字符串，返回所有它能表示的字母组合。答案可以按 任意顺序 返回。
 *
 * 给出数字到字母的映射如下（与电话按键相同）。注意 1 不对应任何字母。
 *
 *
 *
 *
 *
 * 示例 1：
 *
 *
 * 输入：digits = "23"
 * 输出：["ad","ae","af","bd","be","bf","cd","ce","cf"]
 *
 *
 * 示例 2：
 *
 *
 * 输入：digits = ""
 * 输出：[]
 *
 *
 * 示例 3：
 *
 *
 * 输入：digits = "2"
 * 输出：["a","b","c"]
 *
 *
 *
 *
 * 提示：
 *
 *
 * 0 <= digits.length <= 4
 * digits[i] 是范围 ['2', '9'] 的一个数字。
 *
 *
 */

// @lc code=start
function letterCombinations(digits: string): string[] {
  const result: string[] = [];
  const map = new Map([
    ["2", "abc"],
    ["3", "def"],
    ["4", "ghi"],
    ["5", "jkl"],
    ["6", "mno"],
    ["7", "pqrs"],
    ["8", "tuv"],
    ["9", "wxyz"],
  ]);

  const nums = digits.split("");
  const queue = [""];

  for (let num of nums) {
    let chars = map.get(num)?.split("");
    let length = queue.length;
    while (length--) {
      let tempStr = queue.shift();
      chars?.forEach((char) => {
        let str = tempStr + char;

        if (str.length === digits.length) {
          result.push(str);
        } else {
          queue.push(str);
        }
      });
    }
  }

  return result.filter(Boolean);
}

// @lc code=end
